Binary fission

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Binary fission is the form of asexual reproduction used by most prokaryotes and protists to reproduce. This process results in the reproduction of a living cell by division into two equal or near-equal parts.

Binary fission begins with DNA replication. DNA replication starts from an origin of replication, which opens up into a replication bubble (note: prokaryotic DNA replication usually has only 1 origin of replication, whereas eukaryotes have multiple origins of replication). The replication bubble separates the DNA double strand, each strand acts as template for synthesis of a daughter strand by semiconservative replication, until the entire prokayotic DNA is duplicated.

Each circular DNA strand then attaches to the cell membrane, sometimes by a mesosome. The cell elongates, causing the two chromosomes to separate.

The cell membrane then invaginates (grows inwards) and splits the cell into 2 daughter cells, separated by a newly grown cell plate. This process is called cytokinesis.

Binary fission is asexual; offspring are supposed to be genetically identical to the parent cell, but due to mutation, daughter cells may have slightly differed genetic makeups. Bacterial DNA has a relatively high mutation rate. This rapid rate of genetic change is what makes bacteria capable of developing resistance to antibiotics and helps them exploit invasion into a wide range of environments.

Organisms that reproduce through binary fission generally grow exponentially. E coli cells are able to divide every 20 minutes under optimum conditions.

Many organisms reproduce by binary fissions, such as: